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By J. P. W. Bennie, A. de Jong, G. M. Denton

Mintek together with Middelburg Steel & Alloys, developed the DC arc furnace process for the production of ferroalloys with the expressed objective of smelting ore fines (<1mm) without the need for agglomeration. In the case of ferrochrome production, the DC arc furnace, being a semi-open bath operation, loses radiant energy directly from the bath to the furnace roof and sidewalls above the melt. This energy loss is reflected in a higher electrical energy usage per ton of alloy than for a submerged-arc operation smelting lumpy ores or sintered pellets. The difference increases still further when pre-heated sintered pellet feed is used in a submerged-arc operation. This shortcoming of the DC arc furnace can however be overcome by preheating the feed to the furnace in a fluidized bed or flash reactor fuelled by cold furnace off-gas. In addition to fluidization and preheating testwork, various preheating flowsheets with associated mass and energy balances have been developed and compared from a techno-economic viewpoint. The three major advantages identified were: a) fluidized beds can preheat ores and fluxes up to 950°C without sticking and defluidizing, b) the open bath DC arc furnace does not require expensive coke or char to maintain the burden porosity and, c) the capital cost associated with the milling, pelletising and sintering plant falls away since ore fines are used directly.

Jan 1, 2004

By Ifeanyichukwu Nweke

"Aluminium rolling processing from ingots to cold rolled coils comes with a lot of challenges especially in controlling defective products in casting, hot mill and cold mill operations. Hence this study focused on reducing defects at mills and cast-house using six sigma approaches. The use of six sigma approach will help the production experts to determine the gap between its operation and world class process. Practical data from First Aluminium Rolling mills were presented and analysed and mini improvement projects were proposed based on organisation need to achieve excellence. This study encourages aluminium alloy industries to pursue process improvement projects on the basis of analysis on data obtained from their shop floor, hence ensuring that through this, recovery is improved and cost of poor quality is reduced.INTRODUCTION Engineer Bill Smith while working at Motorola in 1986 introduced a new concept in which a set of techniques and tools are used for process improvement by controlling variations (defects). These tools and techniques are explained by an acronym DMAIC. D DEFINE the problem M MEASURE the variables in the problem A ANALYSE the variables of the problem I IMPLEMENT and verify the solution to the problem C CONTROL the solution to sustain it Most times in six-sigma approach, variations in the process that results in defects and customers’ dissatisfaction are targeted at 3.4 defects per million opportunities. There are numerous methods six sigma application use to achieve quality results and innovative strategies. Improving the quality of process through these methods helps identify and reduce variations which paves way for organisational excellence. In this study, it is encouraged to use six sigma techniques to improve aluminium rolling operations and other aluminium processing activities, the benefits of such improvement concept include: • Satisfy the voice of the customer (VOC) • Minimise costs • Maximise Profits • Build Good Team • Implement Profitable Project"

Jan 1, 2018

By Jr. Hazen

This report documents 653 sets of sample data involving 78,366 assays obtained from past exploration for various minerals and metals. Most of these data have been taken from published reports describing exploration projects, conducted jointly by the Bureau of Mines and the Geological Survey, for the Strategic Minerals Program from 1940 through 1949. Means and standard deviations have been computed for the exploration assay data and have been plotted on graphs for 22 minerals and metals. A mathematical model, based on the binomial distribution, has been developed to explain the configuration of the plots of the exploration means and standard deviations. The two statistics, mean and standard deviation, which describe assay data, have been used for simulating probability models. These probability models then have been combined with the binomial model of the exploration assays and related to the sequential decision process associated with exploration drilling for mineral deposits. These probability regions can be used to form the basis for sequentially predicting the probable range of the average grade of mineral or metal that may be expected as an exploration drilling program is continued after the initial discovery of mineralization has been made.

Jan 1, 1966

By K Rau

The overall success of a mining operation is directly impacted by the reliability and availability of mining equipment. Heavy-duty vehicles such as excavators and haul trucks are used for conveying of bulk material and improving such assets’ availability helps reduce costs, increase throughputs and improve safety (Ravande, 2022). If a mining operation’s key performance indicators (KPIs) are tied to operational performance, then overall equipment effectiveness (OEE) is an essential metric to track progress and to identify areas of improvement.

Sep 1, 2024

By Jon K. Ahlness

The Bureau of Mines investigated technologies for testing the integrity of in situ leach mining wells, as required by environmental regulations. To test for leaks, inflatable packers were used to seal the well casing. Laboratory testing determined that the packers could contain a casing pressure up to 50 to 60 psi (345 to 414 kPa) less than the packer inflation pressure. Single-and double-packer configurations were successfully field-tested in 32 wells ranging from 500 to 530 ft (153 to 162 m) in depth. A rigid pipeline and a hoist truck were used to run the packers in and out of the wells for the double-packer tests, which averaged 2-1/4 h each. In an effort to decrease the time of the rigid-pipe double-packer test. a self-contained trailer-mounted test system was designed and built. It utilizes a winch and steel cable to run the packers in and out of the well and high-pressure nylon tubing for packer inflation. This system was successfully field-tested in eight wells averaging 650 ft (198 m) in depth and resulted in a time savings of 13 pct and an operator-hour reduction of 42 pct.

Jan 1, 1985

By M. Hertzberg

The Bureau of Mines measured the energy requirements for the spark ig-nition in air of Pittsburgh seam bituminous coal dust, lycopodium spores, and polyethylene powder with a 1.2-L furnace and 8-L and 20-L chambers. Thermal autoignition temperatures of the same dusts were mea-sured in the 1.2-L furnace. Electrical ignition requirements are given in terms of both effective spark gap energies, [ ] and stored circuit energies, 1/2 CE2. The measured order of electrical ignitability for the three dusts is consistent with the data of other researchers; however, the absolute values are systematically higher, probably because of higher flow and turbulence levels in the chambers used and lower electrical efficiency in the circuit used here. The temperature dependence of the lean limit of flammability for lyco-podium was measured wi th the 1.2-L sys tem, and those measurements con--firm the applicability of the modified Burgess-Wheeler law to a dust. Due to experimental complexities, the minimum ignition energies for dusts may not reflect intrinsic flammability behavior. However, some valuable information may be obtained from the relative ignition energies of various dusts at ambient and elevated temperatures. In addition, the concept of minimum electrical ignition energies for homogeneous gas mixtures is reevaluated theoretically.

Jan 1, 1985

By H. A. Watson

This circular, which is a revision and combination of two previous publications,3 4/ presents information on the different types of equipment that may be used to analyze mine atmospheres, with particular reference to the application and limitations of each type. Such information is frequently requested by mining companies, State mining departments, and other agencies concerned with safety in mining who wish advice regarding methods of analysis of mine atmospheres and the equipment necessary for establishing laboratories for that purpose. Since the Haldane-type apparatus is particularly applicable to the accurate determination of carbon dioxide, oxygen, and combustible gases such as methane in mine atmospheres, that apparatus and the method of operation are described in detail. The circular presents results of a critical study of the accuracy attainable with the Haldane-type apparatus in the determination of methane in concentrations of the order of 0.25 percent, by volume. Analytical procedures involved in the other methods discussed are presented in publications referenced in this circular. Information is given also on the various accessory equipment needed in a laboratory for the analysis of mine atmospheres, and suggestions on laboratory design are included. INTRODUCTION &apos;The analysis of mine atmospheres plays an important part in promoting safety and maintaining safe conditions in mining operations, particularly in coal mining, where the flammable gas methane presents a continuous hazard in Nome mines and may be encountered unexpectedly in others.5/ Methane has been encountered also, often unexpectedly and with disastrous results, in noncoal mines and in tunnels under

Jan 1, 1956

Electronic detonators bring a fundamental and radical change to the potential of rockbreaking operations. The immense technical challenge of safely merging electronic systems with explosives has been largely overcome, but a surprisingly difficult obstacle has been to convert users to the much more capable electronic systems, in routine as opposed to exotic applications. Unit cost is probably the main point of resistance. For years papers have confirmed significant improvements in blasting results, feeding through to enhanced bottom line value for the whole operation: much reduced environmental impact, and improved control over fragmentation, muckpile shape and overbreak. In Africa, a number of operations have been employing the technology for sufficient time to see enduring improvements in throughput, control and cost structure, and these improvements have fed through to the planning process: both the cost and the benefits are part of the plan. This has essentially rendered very unattractive the option of reverting to pyrotechnic systems and incurring the penalties previously unseen but now understood to be avoidable. Examples given are of improved throughput at opencast and underground mines, and greatly extended life at an urban quarry. The general experience of management in implementing the technology is that it over-delivers: adopted to solve one particular problem, significant other issues are also addressed. These extra benefits were quite logical, but not at all obvious prior to implementation. Exploring this reality is essential for harvesting the benefits of the technology sooner rather than later.

Jan 1, 2004

By J. B. Zadra

Much has been published by various investigators on the use of activated carbon for adsorbing precious metals from cyanide solution and pulp. For the benefit of the reader, a list of these earlier publications appears at the end of this report. The present paper deals only with a process for extracting gold from gold-laden carbon and re-use of the de-adsorbed carbon. At the Getchell mine, Redhouse, Nev., experiments have been in progress for several years concerning the use of activated carbon to adsorb gold from their slime circuit pulp. The experimental work has been successful. Their practice has been to ship the gold-laden carbon to a smelter for treatment, which meant the total loss of the carbon in addition to smelter and freight, charges, all of which proved costly and wasteful.

Jan 1, 1950

By E. A. Nesbitt

The important permanent-magnet alloys 15 years ago contained carbon and depended upon it for their permanent-magnet properties. In recent years great advances have been made in a number of new alloys substantially free of carbon. These include Remalloy,&apos; an alloy of iron, cobalt, and molybdenum, the various iron-nickel-aluminum alloys of the Mishima2 type, and the more recent Alnico V3 in which the best properties are developed by heat-treating in a magnetic field. The Mishima and the Alnico types of alloys are very brittle and after casting must be ground to size. This article describes a permanent-magnet material4 that can be machined as cast, and when handled with some care can be rolled to thin sheet and drawn to fine wire. Optimum magnetic properties are developed by a simple heat-treatment, and at this time the ductility of the alloy disappears. If the cast alloy is heat-treated without cold-working the mag netic energy product is about 1.0 X 106. This material is called Vicalloy I (pronounced vicalloy, V for vanadium, I for iron, and C for cobalt). When the alloy is first hot-worked and then considerably reduced in area by cold-swaging, drawing or grooved rolling, it is found that after heat-treatment the magnetic energy product measured in the direction of previous extension can be increased to 2.0 to 3.5 X 106. These higher values have been obtained only after reductions in area of 75 to 95 per cent, and since the material hardens considerably during working, the reduction ordinarily can be accomplished only in fine wires, although larger sizes can be reduced by the use of powerful machinery. When the material has been cold-worked in such a manner as to improve its energy product substantially, it is called Vicalloy 11. Commercial use of Vicalloy has been made in the recording of speech. Tape 0.002 by 0.050 in. has been found superior in quality to all others tried, and is now used in the Western Electric Mirrorphone 5 In a variety of forms Vicalloy I or I1 is useful in many laboratory instruments, and in experiments in which the sizes and shapes required cannot be obtained with the other more brittle permanent-magnet materials. In 1936, during a study of other age-hardening magnetic systems, it occurred to the author that some of the iron-cobalt-vanadium alloys might be suitable for permanent magnets. The proportions of iron, cobalt, and vanadium were varied and a range of alloys of particular interest was found, as shown by the indicated area in Fig. I. The limits of this range of composition are 30 to 52 per cent iron, 36 to 62 per cent cobalt, and 4 to 16 per cent vanadium. The compositions indicated by points outside this area were also tested. Preparation and Properties OF Vicalloy I The alloys were usually cast in graphite molds into bars 3/4 in. in diameter and

Jan 1, 1946

By E. A. Nesbitt

The important permanent-magnet alloys 15 years ago contained carbon and depended upon it for their permanent-magnet properties. In recent years great advances have been made in a number of new alloys substantially free of carbon. These include Remalloy,&apos; an alloy of iron, cobalt, and molybdenum, the various iron-nickel-aluminum alloys of the Mishima2 type, and the more recent Alnico V3 in which the best properties are developed by heat-treating in a magnetic field. The Mishima and the Alnico types of alloys are very brittle and after casting must be ground to size. This article describes a permanent-magnet material4 that can be machined as cast, and when handled with some care can be rolled to thin sheet and drawn to fine wire. Optimum magnetic properties are developed by a simple heat-treatment, and at this time the ductility of the alloy disappears. If the cast alloy is heat-treated without cold-working the mag netic energy product is about 1.0 X 106. This material is called Vicalloy I (pronounced vicalloy, V for vanadium, I for iron, and C for cobalt). When the alloy is first hot-worked and then considerably reduced in area by cold-swaging, drawing or grooved rolling, it is found that after heat-treatment the magnetic energy product measured in the direction of previous extension can be increased to 2.0 to 3.5 X 106. These higher values have been obtained only after reductions in area of 75 to 95 per cent, and since the material hardens considerably during working, the reduction ordinarily can be accomplished only in fine wires, although larger sizes can be reduced by the use of powerful machinery. When the material has been cold-worked in such a manner as to improve its energy product substantially, it is called Vicalloy 11. Commercial use of Vicalloy has been made in the recording of speech. Tape 0.002 by 0.050 in. has been found superior in quality to all others tried, and is now used in the Western Electric Mirrorphone 5 In a variety of forms Vicalloy I or I1 is useful in many laboratory instruments, and in experiments in which the sizes and shapes required cannot be obtained with the other more brittle permanent-magnet materials. In 1936, during a study of other age-hardening magnetic systems, it occurred to the author that some of the iron-cobalt-vanadium alloys might be suitable for permanent magnets. The proportions of iron, cobalt, and vanadium were varied and a range of alloys of particular interest was found, as shown by the indicated area in Fig. I. The limits of this range of composition are 30 to 52 per cent iron, 36 to 62 per cent cobalt, and 4 to 16 per cent vanadium. The compositions indicated by points outside this area were also tested. Preparation and Properties OF Vicalloy I The alloys were usually cast in graphite molds into bars 3/4 in. in diameter and

Jan 1, 1946

By Andy L. Shaffer

A novel liquid settlement system (LSS) was installed in advance of mining at a western United States (U.S.) longwall mine to measure total roof sag from the time of cutting to days after mining during gate road development. The system was used to compare differences in roof sag between conventional place-change mining using a Joy continuous miner and a Fletcher roof bolter and mining using a miner-bolter. The LSS was installed with an intrinsically safe, miniature data acquisition system (MIDAS) to record roof response at four locations in the same gate road. The system utilized pressure transducers to measure roof sag by the principle of falling head (fluid pressure) in fluid-filletubes installed in the immediate roof. Details of the LSS design, installation, data collection, post-processing, and future applications are discussed.

Jan 1, 2014

By Richard A. Thomas, Connor B. Brown, Thomas H. Dubaniewicz, Teresa Barone

Electric vehicles powered by lithium-ion (Li-ion) batteries are being developed by mining vehicle manufacturers as a replacement for diesel-powered vehicles. Explosion-proof (XP) enclosures are frequently employed to enclose electrical ignition sources in gaseous underground mines to prevent the spread of an internal methane-air explosion to a nearby explosive atmosphere. Due to thermal runaway (TR), Li-ion batteries have the potential to cause pressurized explosions in an enclosed structure. Past research has shown the potential for well-confined Li-ion cell TR to drive pressures beyond the conventional pressure specification for XP enclosures. Researchers at the National Institute for Occupational Safety and Health (NIOSH) used an Accelerating Rate Calorimeter (ARC) to induce thermal runaway of Lithium Titanate or Lithium Titanium Oxide (LTO) type 18650 cells enclosed within containers with various volumes and found an inverse power relationship between the TR pressure and available free space. The results were similar in magnitude to that of lithium iron phosphate (LFP) cells, which were used in prior testing. Temperatures, gas amounts, and TR pressure-rise rates were also recorded. The data indicate that with enough free space, the pressures can be lowered below the conventional pressure specification for XP enclosures.

Feb 1, 2024

By D Syme

In the middle of 2000, BHP Billiton implemented a Six Sigma Plus business improvement program known as Operating Excellence. It was developed based on a business bottom line initiative to deliver 35 - 40c/share and was one of the BHP Billiton strategies to deliver $2 earnings per share and a longer term $40 share price (BHP share price). Cannington is a silver, lead and zinc mine owned and operated by BHP Billiton. Through implementing Six Sigma Plus Cannington wanted to:have in-house capabilities to change and improve; tailor for the needs of each business unit and department; have æSharing of its KnowledgeÆ as a tool for improvement and have a competitive edge across Cannington û to be better than our competitors; learn from and leverage off the successes of improved safety and prior business improvement efforts; and ensure networking and sharing of information have common measurement systems across all assets. As with most business improvement programs û Six Sigma Plus was met with some degree of skepticism, especially given the amount of resources involved. After 18 months, much of this skepticism has been replaced with enthusiasm as peopleÆs understanding and acceptance of its fundamental concepts are being realised. The idea behind Six Sigma Plus is that it combines sound technical solutions with high acceptance by those who need to work with or implement the change. The future vision for Six Sigma Plus is that it become part of what we do at Cannington û just like safety and environment û so that Six Sigma tools and methodologies are used in our every day work.

Jan 1, 2002

By D. A. Hill

A survey of the literature on ELF and VLF atmospheric noise has been made. Most measurements have concentrated on the vertical electric field and the horizontal magnetic field rather than the vertical magnetic field which is of interest in transmission between horizontal loops. The limited vertical magnetic field data indicates that the vertical component is generally 10 to 20 dB below the horizontal component. Three laterally inhomogeneous earth models have been analyzed for conversion of horizontal to vertical magnetic field. The rough surface model examines surface effects, the inhomogeneous thin sheet model treats volume effects, and the buried cylinder model treats localized man-made effects. All three models predict the possibility of significant conversion from horizontal to vertical magnetic field. A thin sheet model has also been used to examine transmission from a buried magnetic dipole source. It is found that the predicted fields more nearly model the measured data than does the homogeneous half-space model.

Jan 1, 1982

By T. K. Mukcherjee

The importance of the processing of secondary resources such as solid industrial wastes and liquid effluents as well as byroducts for the recovery of the associated metal values hardly needs any elaboration. Such processing contributes in no small measure.towards the augmentation of the availability and the supply position of resources. As an added benefit, it leads to a reduction in environmental pollution caused by the undesirable waste materials. As some typical examples of secondary resources in the Indian scenario, mention&apos; can be made of spent catalysts, metal/alloy scrap, ash, consumed batteries, flue dust, slag, sludge and slime, pickling solutions, spent acids; plating rinse solutions, spent etchants, waste water from synthetic fibre manufacture and from tanneries etc. These wastes constitute a source of a variety of non ferrous metals. In the processing of secondary resources like these, the techniques of hydrometallurgy such as solvent extraction play a pivotal role. This paper outlines the efforts made to use solvent extraction to recover(1) base metals. such as copper, zinc, nickel and cobalt from a number of secondary resources like cake, and sludge(2) refractory metals like molybdenum and vanadium from sulphidic byproducts and spent catalyst and (3:) nuclear metal like uranium from phosphoric acid. In the case of base metals, process flowsheet involving the use of acidic extractants such as DEHPA and PC88A have been optimised. The problem of iron removal from the leach liquor, "which influences the metal recovery process significantly, has drawn a special emphasis. hi the case of refractory metals, basic extractants .like Alamine 336 has been pressed into service to produce kilogramme. quantities of pure salts of molybdenum and vanadium, Finally, the paper gives a brief account of plant experience in recovering uranium from phosphoric acid, using &apos;a solvent system comosed of DEHPA and TOPO.

Jan 1, 1996

By M-d-N. Gagnon, P. Okono, Y. Bergeron

In the mining industry, decisions regarding the type and number of comminution tests to be completed typically rely on geologists? observations and conclusions when studying drill cores. Given that these decisions are based on visual observations, they are essentially approximate and often inaccurate from a comminution viewpoint, causing a sizeable margin of error in estimating characterization test needs. Consequently, companies are often forced to perform more tests than necessary, requiring a significant quantity of material, and accruing significant costs. Recently, a new device, called the Hardness Index Tester (or HIT), was developed, offering users a low cost in-house mechanism for estimating the comminution parameter A*b and the Bond Ball Mill Work Index at any mine site, with potential applications on fragments up to 25 mm from drill core. In late 2016, Agnico Eagle Mines Limited initiated a trial to investigate if having an HIT device installed in a core repository would make it possible to identify the different rock properties more accurately and determine the number and type of comminution tests required. The application of the HIT was not to replace the standard comminution tests, but rather to generate a high number of comminution and geomechanical parameters for the rock mass. Ultimately, the objective would be to determine the uniformity of the rock mass and, therefore, easily distinguish any potentially problematic zones. With this method, the appropriate number of standard tests could be determined, making the HIT not only an excellent complement to the standard laboratory tests, but also an indispensable device for a geometallurgical characterization. This paper presents the results from the HIT trial using samples from the Odyssey Project, which is a Mine Canadian Malartic property.

Jan 1, 2017

By K. W. Grubaugh, L. W. Saperstein

The recently enacted federal surface mine law (P. L. 95-87) increases further the complexity of securing a reclamation permit This law intensifies the need to present the required reclamation plan in a thorough and comprehensive manner. One plan format, that used in construction performance contracts, offers promise of filling this need. Reasons for using the format of expressed, bilateral, negotiated contracts common to the construction industry, and the salient aspects of an application which uses this format are reviewed. Advantages of this procedure are seen to be improved mine planning, awareness of the total design job, potential for improved speed of permit acceptance, and improved cost control.

Jan 1, 1981

By William P. Diamond

In this U.S. Bureau of Mines study, production trends have been analyzed for 82 gob gas ventholes on 7 longwall panels in the Lower Kittanning Coalbed, Pennsylvania. Cumulative production from individual holes was found to vary considerably, ranging from 0.03 x 106 to 10.1 x 106 m3. Peak production rates were generally about 0.03 x 106 to 0.06 x 106 m3/d, but rates over 0.10 x 106 m3/d were observed. The variability of gas production from individual holes can be attributed to&apos; several factors, including completion practices and problems, the extent of fracture development in the strata above the extracted panel, water production, and location on the panel. Of particular significance is hole location. Holes on the ends of the panels, where overburden strata are in tension because of the support of the surrounding pillars, were generally the highest and longest producers. This observation led to the experimental placement of gob gas ventholes in the zone of tension along the margin of a panel, instead of in the traditional centerline location, which is in compression. Analysis of 7 months of gas production data indicates that the experimental near-margin holes produced 77 pct more gas than did centerline holes on the same panel.

Jan 1, 2010

The history of mining is rightly proud of its achievements in improving productivity and cost improvements over the years. No matter what measure is used, tonnes per manhour, cost per tonne, etc vast improvements have been made over the last hundred years. In fact over the last ten years in Australian coal mines raw coal output per employee has increased by 60 per cent. When one examines why these improvements have taken place the principal reasons have been technological advancement in mining equipment, excavator and dump truck capacity increases, longwall and continuous miners continually improving in reliability and size. Of course all these improvements are correlated to an increase in capital cost. Even with the above-mentioned advances the pressure for increased performance is as strong as ever. The international mining and mineral-processing sector is currently operating in a recessive market with some traditional commodities, eg gold trading at 20 year lows. During recessive times senior management will demand greater returns on capital employed: the obvious choices being reducing costs or increasing throughput. In addition, head office environments will often place a capital freeze on operational management so the opportunity to take advantage of technological change is not available. The challenge is, therefore, to increase throughput and cut costs without the need for capital. The answer is to optimise the existing labour and plant. If done systematically a result in productivity improvement, in our experience, as high as 45 per cent can be achieved with the average across South East Asia and Australasia being 21 - 23 per cent. The intention of this paper is to present a systematic approach to labour and machine utilisation thereby gaining the greatest possible return on the existing capital base.

Jan 1, 1999